Alternative Character Interpretation: Are the Metroids mindless predators hunting through pure instinct? Or are they fiercely protective of their own kind, but also territorial? Note that the behavior of the Metroid Queen is that she roars in pure rage after you kill her larva hatchlings before you make it to her chamber. And then there's the hatchling that saw Samus, thinking she is its mother. Which according to Samus, floated around her like a confused child. There's another whether the Chozo programmed them that way.
And You Thought It Would Fail: Excitement for Samus Returns quickly diminished into caution when it was learned that it was being co-developed by MercurySteam, which had previously worked on the divisive Castlevania: Lords of Shadow series. Many who didn't like the Lords of Shadows games or were at least aware of how Lords of Shadow 2 was critically panned were skeptical of Nintendo choosing them as a development partner, with some even going as far to say that this was a sign that Nintendo was deliberately trying to kill the franchise for good with this decision. Yoshio Sakamoto's involvement as producer also put off fans due to his previous work on the controversial Other M resulting in many believing that he should never touch the franchise ever again. Nintendo filing a DMCA takedown against Another Metroid 2 Remake the previous year also didn't help, with some Metroid fans wishing for this game to fail out of spite because of it. Despite all of this, however, Samus Returns garnered very positive reception upon release, with many fans agreeing that it was a return to form for the franchise.
Awesome Music: Kenji Yamamoto is back in form, directing the musical themes here; the arrangements were made by Daisuke Matsuoka.
Arachnus, of all the bosses, got a completely new song not based on his usual theme from Fusion. It's surprisingly funky and fun for such a short-lived battle.
The final boss - allthreephases. They're all based on different iterations of Ridley's themes over the years; first his usual theme from Super, second his Meta Ridley theme from Prime, and third the Neo Ridley theme in Fusion. And of course it's going to be awesome anyway — it's Ridley.
The Queen Metroid boss theme, which is a much more terrifying song than the original's theme for the Queen, even incorporating a Dark Reprise of said original theme around a minute in. It also carries quite a bit of inspiration from Mother Brain's theme, having a similar beat and even having identical instruments.
The inclusion of Ridley as a Post-Final Boss. The debate isn't about whether it was a good boss battle, as even detractors agree that it is one of the best in the series. The debate comes from whether it belongs in Metroid II. Some like how its design indirectly finally confirms inside a game once and for all that the Metroid Prime Trilogy is canon (which settled a long-lasting debate in the fandom), how it strengthens the bond between Samus and the baby Metroid in a Show, Don't Tell manner, and how it serves as retroactive foreshadowing for Super Metroid. However, others believe the fight is a Giant Space Flea from Nowhere with zero setup that is an obvious example of Pandering to the Base, and hate how it significantly alters the more somber tone of the game's ending, which was originally a quiet sequence of Samus and the baby Metroid peacefully traveling back to the gunship together.
The final boss debate ties into a larger one concerning how the game compares to the original Game Boy game. The argument is less about if Samus Returns is a good game, and mainly questions if it is a good remake. Opponents argue that it made too many changes to the tone, atmosphere, and even level design of the original Metroid II to be viewed as such. Proponents argue that the game is faithful enough to the original, with it retaining a largely dark and atmospheric soundtrack, including some surprisingly well-done remixes of the original's cave ambience; its emphasis on action and combat against aggressive enemies serving the original's themes; its expanding upon the worldbuilding and lore of SR388, with additions such as the Chozo Laboratory or the shifting ecosystem after the Metroids' extermination; and iconic moments such as Samus's encounter with the baby Metroid being faithfully recreated with even greater presentation.
Canon Fodder: The Chozo that killed the SR388 Chozo at the end of the Chozo Memories gallery. Their motivations, be they a rouge faction, wanting to use the Metroids or X Parasites for their own ends, carrying an exemplary punishment for the Metroid outbreak, or suspicious that the SR388 Chozo could be X Parasites mimicking them, was a big source of fan speculation before Metroid Dread picked up this cliffhanger and gave proper context to it.
Catharsis Factor: Whether you thought Diggernaut was a fair challenge or a frustrating endeavor, everyone can agree that seeing Samus finishing it off with an Offhand Blast is immensely gratifying.
Common Knowledge: Most likely due to the prevalence of Gulluggs (and, to a lesser degree, Hornoads and Motos), it's often said by fans that every single common enemy encounter in the game forces Samus to use the Melee Counter. In actuality, more than half of the game's enemy types (including electric variants of Gulluggs and Moheeks) do not perform any attacks that can be countered, requiring Samus to rely on other means of defeating them. Moreover, outside the tutorial that formally introduces the maneuver, you're never required to counter any enemies to defeat them (though doing so is the safest and fastest method for most of the game).
The bat-like Gulluggs deal a surprisingly large amount of damage to Samus and are very common, making it extremely easy to quickly lose a lot of health to them if you haven't mastered the melee counter yet or are trying to speed run through the game. The fact that they change colors as they become more powerful doesn't really help. If you find the blue and pink Gulluggs manageable, the electric Gulluggs are even worse, as they cannot be melee countered and you can get damaged even while using the Screw Attack.
While their attack and movement pattern is the same as the original, the fly-like Drivels are much more aggressive and will actively try to stay above you so they can drop their acid on you. These guys appear as early as Area 1 and can be really deadly, especially if you're focusing on another enemy in their territory. They are one of the few early game enemies that can take a lot punishment and cannot be hit with the melee counter due to hovering right out of the counter's range and attacking only with projectiles.
Fandom Rivalry: With the well-known unofficial remake of Metroid II, Another Metroid 2 Remake. Supporters of Samus Returns point out its 2.5D presentation, new gameplay mechanics, greater cinematic presentation, and the fact that it's an official remake as advantages. Fans of AM2R, on the other hand, decry Samus Returns for having ugly 3D models as opposed to AM2R's pixel art, unnecessary new mechanics that don't fit Metroid, and having more cinematic cutscenes. Part of the rivalry also extends to Nintendo's takedown of AM2R, with some of that game's supporters planning to boycott Samus Returns in retribution. Of course, these people are a Vocal Minority. The Silent Majority on the other hand is an example of Friendly Fandoms.
Fanon: Throughout the game, Samus encounters a mysterious crystalline substance that she cannot destroy with any of her weapons. Since the baby Metroid is shown effortlessly shattering said obstacle simply by touching it, a popular fan theory is that the crystals are actually dormant X-Parasites, which the baby, as their natural predator, is instinctively drawn to.
Goddamned Bats: Autoads may simply crawl instead of hopping around like in the original game, but now they have exchanged their erratic movement patterns for an EMP-like attack that can temporarily disable your Aeion abilities and drain away your Aeion gauge, and they can take a lot of punishment. Just when you think having the Plasma Beam makes the bronze Autoads a pushover, the silver ones are even worse, as they are nearly invulnerable to everything except Power Bombs (which you only get late in the game) and Beam Burst (which the silver Autoads can easily nullify before the shots start bursting through their armor).
Goddamned Boss: Omega Metroids move slow enough to be easy to dodge, have widely telegraphed attacks and generally are easy to run circles around once you encounter one. However, they make up for this by having mountains of HP in addition to having a regenerating chest plate you need to destroy first, which you only have very limited openings to hit and their attacking animations take up a good amount of time to play out. All this results in fights that go on longer than needed without much actual threat to them.
Ridley being in this game as the final boss despite not being in the original Metroid II at all.
The Chozo Memories gave the first glimpse of the long-awaited Metroid Dread, specifically a preview of the new Big Bad Chozo, Raven Beak, and his Mawkin tribe.
Minimalist Run: It's entirely possible, albeit very difficult, to complete the game with 0% (no optional items collected) and without certain power-ups like the Spider Ball and Hi-Jump Boots.
Moment of Awesome: Successfully countering a Metroid actually leads to a short animation where Samus gets to display all her badassery.
Narm: While it is an awesome moment, the way the Baby Metroid charges at Ridley to save its adopted mother looks a bit silly when you can see its baby teeth while it dashes towards him. This is the whole point, since despite the little beast's bravery, a newborn Metroid's undeveloped fangs wouldn't even hold on to Samus let alone something as strong and violent as Ridley, otherwise the fight would be too easy.
There was a Counter-Attackfeature in Other M. This game simply improves upon that mechanic by allowing it to work against any enemy melee attack with a visual cue (as opposed to a select few enemy attacks with no in-game indications as to which ones; Samus Returns also provides visual cues for when they won't work such as an enemy being coated in electricity), providing in-game tutorials for the mechanic (as opposed to having it All There in the Manual), having a single-button dedicated to it (as opposed to having it a share the same button as your primary attack as a result of the Wiimote-only control scheme, and again, only activating against specific attacks) and providing greater rewards for executing it (the potential to One-Hit Kill an unprotected enemy after executing it, getting free hits on bosses, and extra Aeion energy to recover, whereas in Other M, it wasn't always practical to deliberately exploit and of the enemies it could be used against, it was only really effective on a few of them).
The Nintendo Power Source interactive online non-canon story Blood of the Chozo was actually the first Metroid-related work to feature a villainous faction of Chozo.
Overshadowed by Controversy: Samus Returns will always seem to live in the shadow of Another Metroid 2 Remake, the Fan Remake that Nintendo shut down with a controversial DMCA to prevent it from potentially cutting into the official remake's sales. Any discussion on Samus Returns will inevitably result in AM2R being brought up as the elephant in the room, with many Metroid fans unfavorably comparing the $40 official remake to the free fan game and upholding the latter as the superior remake.
Scrappy Mechanic: The Melee Counter has gained some criticism for how it works - while it lets you parry oncoming enemy attacks and retaliate with heavy damage, it cannot be used while moving. Instead, you have to stand still and wait for the enemy to come to you before you can use the counter. Mildly annoying for the average player, but for speedrunners, the "stop and go" nature of the Melee Counter makes it waste precious seconds when trying to run as fast as possible. Metroid Dread managed to remedy this by allowing Melee Counter usage while moving, throwing speedrunners a bone and also allowing it to feel much snappier.
Sequel Difficulty Spike: Samus Returns is much harder than previous Metroid games thanks to nearly every enemy rushing Samus on sight and damage being much higher, with bosses and stronger Metroids easily doing a tank's worth of damage or more per attack, even with the Gravity Suit, on Normal Mode.
Tainted by the Preview: When it was confirmed that the game's Fusion mode (essentially a Hard Mode) will be locked behind a Metroid amiibo, sold separately. Most players shrugged off other features being locked the same way (such as the Sound test room), but having a game mode locked that way led to some furious reactions. This was toned down a bit when Nintendo clarified that Fusion Mode is actually a Harder Than Hard mode while a traditional hard mode can be unlocked by beating the game.
That One Boss: Diggernaut has hard-to-dodge attacks that take off multiple energy tanks, no chances of recovery outside of Phase 2, and has not one, but three Spider Ball puzzles that require precise timing. It can bring back bad memories of the Spider Guardian. It also has multiple hair tearing-ly frustrating parts. When it performs the suction move, missiles do nothing, but bombs, which are far weaker than missiles do. Worse, the Spider-Ball mode locks you into the ground so you can avoid the suction, even though almost every other thing in the game knocks you around, even your own bombs.
The Diggernaut escape scene in Area 4 is surprisingly unforgiving. It's easy to commit mistakes due to the layout and enemy placement of the tunnels you have to dash through, with the game showing very little leniency if you screw it up. Get caught by the Diggernaut and it's back to the last checkpoint with you.
In a larger scale, Area 3 is considered a low point for many players, due to only containing one new suit ability and TEN Metroids spread throughout an enormous map. Several of those Metroids also have the ability to escape to different rooms every time they take a certain amount of damage, requiring you to track them down again to continue the fight.
Nearly half of the common enemies in the original Metroid II were Adapted Out of Samus Returns as opposed to giving all of them full 3D makeovers. This has disappointed some fans, as they feel that Samus Returns has poor enemy variety compared to other games in the series.
In Metroid II, with only a few exceptions (Arachnus, TPO, and Proboscum), most fauna were exclusively located in caves and tunnels, while most robots were exclusively located inside ruins; Metroids were the only enemies who could be found in ruins after first encountering them in caves, subtly hinting at their artificial origins. While the line between "cave" and "ruins" is blurred in Samus Returns, there is hardly any thematic placing of enemies, with fauna and robots appearing together in any given room. Furthermore, Metroid II takes a turn for the somber the deeper you go, with the planet's life forms becoming smaller and weaker the closer you get to the hive; similarly, the game ends with a peaceful walk to the surface. In Samus Returns, enemies become more aggressive and tightly packed, and continue to appear well within the hive and after the battle with the Queen. Some feel these choices in enemy placement undercuts some of II's narrative themes in the name of serving the combat.
In Metroid II, the last Chozo statue (which formerly held the Ice Beam, the Metroids' weakness) is found destroyed in the Metroid hive, a chilling scene implying that the Chozo were killed by their own Metroids. In Samus Returns, the broken Chozo statue appears much earlier in Area 4 as debris left behind by Diggernaut, and it formerly held the Space Jump instead of the Ice Beam. Consequently, these changes completely drop the statue's implications for the relationship between Chozo and Metroids, which is instead relegated to the Chozo Memories.
They Wasted a Perfectly Good Plot: While the Ridley fight itself has been very well-received, some fans feel that it would have been better if the encounter had a proper build-up. For example, the game could have had a Space Pirate party land on the planet in order to gather Metroids, and then engage Samus as she tries to make her way back to her ship. Alternatively, the fight could have been a remake of the prologue of Super Metroid aboard Ceres Space Station, just with Ridley promoted to an actual boss instead of a tutorial encounter.
Ugly Cute: The baby Metroid at the end of the game is now as hideous and adorable as ever thanks to the 3D presentation.
After the poorly-received Metroid: Other M, Metroid Prime: Federation Force, and the DMCA takedown of Another Metroid 2 Remake, most of the fanbase was convinced that the series was as good as done. The E3 2017 announcement of Samus Returns (alongside Metroid Prime 4) went a long way to showing them that the franchise was not dead, and was coming back in a big way.
Once the initial hype from the announcement had died down, several concerns were raised about Samus Returns, since it was developed by MercurySteam (known for their divisive Castlevania games) and produced by Yoshio Sakamoto (who was responsible for the most controversial elements of Other M). The fact that some fans were worried this game was rushed in an attempt to quickly quell the fan outrage following Federation Force certainly didn't help matters. After the game was released however, these concerns were laid to rest, with MercurySteam and Sakamoto being redeemed in the eyes of many fans.
(which was also used in the E3 2017 trailer) is perhaps one of his best works yet.